Waves What are waves?????

Waves Definition: waves are a disturbance that transfers energy from place to place.

What carries waves? A medium, a medium is the material through which a wave travels. A medium can be a gas, liquid, or solid.

Mechanical Wave Definition – waves that transfer energy through matter.

Wave traveling through a gas! a solid – an earthquake! Wave traveling through a liquid!

Not all waves require a medium to travel Not all waves require a medium to travel. Light from the sun travels through empty space. Light waves are NOT mechanical waves.

How does light travel in space? Light travels as a wave. But unlike sound waves or water waves, it does not need any matter or material to carry its energy along. This means that light can travel through a vacuum—a completely airless space. Nothing travels faster than light energy. It speeds through the vacuum of space at 186,400 miles (300,000 km) per second.

What causes waves? Waves are created when a source of energy causes a medium to vibrate. A vibration is a repeated back and forth or up and down motion.

Types of Waves Waves are classified according to how they move and by the medium they travel through.

Transverse wave – page 1 Waves that move the medium (matter) at right angles to the direction in which the waves are traveling is called a transverse wave. Transverse means across. The highest parts are called crests the lowest parts are called troughs.

Longitudinal Wave –page 1 (also called a compression wave) Matter(the medium) vibrates in the same direction as the wave travels.

Longitudinal Wave –page 2 The parts, where the coils are close together are called compressions, the parts where the coils are spread out are called rarefactions.

Longitudinal Wave –page 3

Combinations of waves Surface waves are a combination of transverse and longitudinal waves. The waves occur at the surface between water and air.

Slinky Teacher demonstration of waves using Slinky!!!!( I have some in my closet!!!) Student - active demonstration of Transverse & Longitudinal waves

Project #1 Draw Transverse wave: label: crest & trough Draw a Compressional wave: label: compression& rarefaction

Science Text Book pages C-9 to C - 14 Partner/individual Read and Respond to the questions on your guided notes as you read. Due end of class!!!!!

Properties of Waves

Basic Properties of Waves Amplitude Wavelength Frequency Speed

Amplitude Amplitude is the maximum distance the particles of the medium carrying the wave move away from their rest positions. The farther the medium moves as it vibrates the larger the amplitude of the resulting waves. The greater the amplitude the greater the amount of energy.

Amplitude of transverse waves The amplitude of a transverse wave is the maximum distance the medium moves up or down from its rest position. You can find the amplitude of a transverse wave by measuring the distance from rest to crest or rest to trough.

Amplitude of a longitudinal wave. The amplitude of a longitudinal wave is a measure of how compressed or rarefied the medium becomes.

Amplitude of a Longitudinal Wave another view!!!

Project #2 On your illustrations: Label the AMPLITUDE of each of your waves !

Wavelength A wave travels a certain distance before it starts to repeat. The distance between two corresponding parts of a wave is its wavelength. Transverse waves measure wavelength from crest to crest or trough to trough. Longitudinal waves measure wavelength from one compression to the next.

Project # 3 On your illustrations: Label the wavelength of each of your waves !

Frequency The number of complete waves that pass a given point in a certain amount of time. The number of vibrations per second. Frequency measured in hertz (Hz).

Frequency - page 2

Speed The time it takes for a wave to get from one point to another. Different types of waves travel at different speeds. Waves in different mediums travel at different speeds. For example, light waves travel through air faster than sound waves travel through air. Thunder and lightning –you see lightning before you hear thunder.

Seismic Waves vs. Sound Waves Seismic waves, earthquake waves, are a type of sound wave, so both seismic waves and sound waves travel through the same medium at the same speed. However, if we compare sound waves traveling through the air with seismic waves traveling through the earth, the speeds would be different. Seismic waves travel through the earth at a much higher speed than sound waves travel through the air.

Science Text Book pages C 16- C 21 Partner/individual Read and Respond to the questions on your guided notes as you read. Due end of class!!!!!

INTERACTIONS OF WAVES

Interactions of Waves Ways Waves Interact Reflection Refraction Diffraction Interference Constructive Destructive

Reflection When a wave hits a surface through which it cannot pass, it bounces back.

Examples of reflection Mirror Echo Ball against a wall

Refraction Refraction is when a wave moves from one medium into another medium at an angle, it changes speed as it enters the second medium which causes it to bend. The bending of waves due to a change in speed is called refraction. Though all waves change speed when they enter a new medium, bending occurs when one side of the wave enters the new medium before the other side

Refraction What are the two mediums?

Diffraction When a wave passes a barrier or moves through a hole in a barrier it bends and spreads out.

Interference Constructive interference occurs whenever two waves combine to make a wave with a larger amplitude.

Destructive interference when the amplitudes of two waves combine producing a smaller amplitude.

Science Text Book pages – C 24- C28 Partner/individual Read and Respond to the questions on your guided notes as you read. Due end of class!!!!!